Re: Why does microwaving bread make it chewy and/or hard?

Microwaving makes bread chewy and/or hard (i.e. stale) because it turns water in the bread to water vapor. The water vapor leaves the bread reducing it's water content.

Here is a link to a great bread staling experiment:
http://www.theteacherscorner.net/lesson- plans/science/experiments/sbread.htm

Here is a link to another madsci posting on a related topic:
http://www.madsci.org/posts/archives/1999-08/936074368.Ch.r.html